CHAPTER VIII. 



FUKTHER EXPERIMENTS ON MOVEMENT. 



Section A. Stimulus of contact, chemical agency, moisture, 

 changes in illumination and in temperature. 



Section B. Autonomous movements : Periodicity. 



Section A. Stimulus of Contact, &c. 



(230) Tendrils: sensitive to contact. 



Among the most sensitive of tendrils are those of 

 Sicyos angidatus, Passiflora gracilis and Echinocystis 

 lohata: the common bryony (Bryonia dioica) is however 

 more generally accessible, and being a native plant requires 

 in ordinary summer weather no special arrangement with 

 regard to temperature. Avoid the very young tendrils 

 and select one with a slight hook at the end. With a 

 pencil or rod rub the inside of the terminal part of the 

 tendril for a minute. It will almost at once show signs of 

 curvature, and will be strongly curved in 2 minutes, — so 

 that for instance the terminal 15 mm. form a complete 

 ring of 3 or 4 mm. in diameter. 



